Change colour using for loop.

Question

Sir this is my static data with html with different different section

<div class="topclr"> --this section show orange colour
<h2> Basic</h2>
<h3> Monthly $299</h3>
<p>Annualy $2990</p>
</div>
<ul id="oran">
@*<i class="bx bx-check" style="color: #FCA121;"></i>*@
<li>lorem ipsum</li>
<li>lorem ipsum</li>
<li>lorem ipsum</li>
<li>lorem ipsum</li>
<li>lorem ipsum</li>
<button class="choose" type="button">Choose Plan</button>
</ul>
</div>
</div>
</div>
<div class="col-md-4">
<div class="back-color">
<div class="plan">
<div class="topclr1"> -- this section black colour
<h2> Standard</h2>
<h3> Monthly $399</h3>
<p>Annualy $3990</p>
</div>
<ul id="grey">
<li>
lorem ipsum
</li>
<li>lorem ipsum</li>
<li>lorem ipsum</li>
<li>lorem ipsum</li>
<li>lorem ipsum</li>
<button class="choose1" type="button">Choose Plan</button>
</ul>
</div>
</div>
</div>
<div class="col-md-4">
<div class="back-color">
<div class="plan">
<div class="topclr2"> -- this section bluee colour
<h2> Premium</h2>
<h3> Monthly $499</h3>
<p>Annualy $4990</p>
</div>
<ul id="blue">
<li>lorem ipsum</li>
<li>lorem ipsum</li>
<li>lorem ipsum</li>
<li>lorem ipsum</li>
<li>lorem ipsum</li>
<button class="choose2" type="button">Choose Plan</button>
</ul>
</div>
</div>
</div>
</div>

But i have use this code with foreach loop

for (var i = 0; i < response.items.length - 1; i++) {
html += '<div class="col-md-4">';
html += ' <div class="back-color" >';
html += '<div class="plan">';
html += '<div class="topclr">'; --bcz here call topclr class
html += '<h2> ' + response.items[i].name + '</h2>';
html += '<h3>' + response.items[i].interval + + response.items[i].unitAmount + '</h3>';
html += '</div>';
html += '<ul id="oran">';
html += ' <li></li>';
html += '<button class="choose" type="button">Choose Plan</button>';
html += '</ul>';
html += '</div>';
html += '</div>';
html += '</div>';

three section display same colour.So i want to display three section with different-2 colour